气雾化高纯镁粉的制备及其水解制氢性能

为了解决镁粉与水反应氢产量低的问题,采用紧耦合真空气体雾化技术制备了高纯超细镁粉,研究了反应条件对镁与水反应制氢效率的影响,并借助X射线衍射仪和扫描电镜对粉末的物相和形貌进行了表征。研究结果表明:球磨转速的适当提高,有助于提高Mg粉的反应活性,当转速为450 r/min时,球磨1 h的氢产量可达到20 mL/g。提高反应水温,水解反应的氢产量会显著升高,水温为70℃时的氢产量可达30 mL/g。水中加入适量的乙醇,有助于提高氢产量,体积分数5%乙醇溶液的氢产量高于体积分数1%和10%乙醇溶液的氢产量。

Highly efficient Z-scheme WO_(3-x) quantum dots/TiO_2 for photocatalytic hydrogen generation

Z-scheme semiconductors are a promising class of photocatalysts for hydrogen generation.In this work,Z-scheme semiconductors composed of WO3-x quantum dots supported on TiO2（WO3-xQDS/TiO2） were fabricated by solvothermal and hydrogen-reduction methods.Characterization by transmission electron microscopy and X-ray diffraction indicated that the amount and size of the WO3-x QDs could be tuned by modulating the addition of the W precursor.Evidence from X-ray photoelectron spectroscopy and photoluminescence spectroscopy suggested that the hydrogen reduction of the composite induced the formation of oxygen vacancy（W^5＋/Vo） defects in WO3.These defects led to ohmic contact between WO3-x and TiO2,which altered the charge-transfer pathway from type Ⅱ heterojunction to Z-scheme,and maintained the highly reductive and oxidative ability of TiO2 and WO3-x,respectively.Therefore,the Z-scheme sample showed 1.3-fold higher photoactivity than pure TiO2 in hydrogen generation.These results suggest that the formation of W^5＋/Vo defects at the interface is highly beneficial for the fabrication of Z-scheme photocatalysts.

Metal-free graphene quantum dots photosensitizer coupled with nickel phosphide cocatalyst for enhanced photocatalytic hydrogen production in water under visible light

Photocatalytic hydrogen(H2)evolution is a promising approach for future sustainable energy utilization.However,it is still a great challenge to develop efficient and stable metal‐free photocatalysts with broadband solar absorption in the visible region for H2 production.Metal‐free graphene quantum dot(GQD)is an emerging candidate for this purpose because of its good water‐solubility and tunable band gap.On the other hand,metal phosphides(Ni2P,Co2P,etc)have been demonstrated as novel noble‐metal‐free cocatalysts for water splitting,which can efficiently separate electron‐hole pairs and enhance the photocatalytic activities.Herein,we report for the first time on the use of OH‐functionalized GQDs(OH‐GQDs)photosensitizer coupled with Ni2P nanoparticles for photocatalytic H2 production withλ>420 nm light.The H2 production rate is^94 times higher than that of bare OH‐GQDs,which is even comparable to that of OH‐GQDs with 1.0 wt%Pt cocatalyst.This enhancement is probably due to the semiconductor‐cocatalyst interface interaction between Ni2P and OH‐GQDs to facilitate efficient charge transfer process.

Photocatalytic H2 generation via CoP quantum-dot-modified g-C3N4 synthesized by electroless plating

Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have been rarely reported.Herein,a CoP co-catalyst-modified graphitic-C3N4(g-C3N4/CoP)is investigated for photocatalytic water splitting to produce H2.The g-C3N4/CoP composite is synthesized in two steps.The first step is related to thermal decomposition,and the second step involves an electroless plating technique.The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots(QDs).Among the as-synthesized samples,the optimized one(g-C3N4/CoP-4%)shows exceptional photocatalytic activity as compared with pristine g-C3N4,generating H2 at a rate of 936μmol g^-1 h^-1,even higher than that of g-C3N4 with 4 wt%Pt(665μmol g^-1 h^-1).The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm,but after being composited with CoP,g-C3N4/CoP-4%has an absorption edge at 497 nm.Furthermore,photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation,but also improves the transfer of photogenerated e--h+pairs,thus improving the photocatalytic performance of the catalyst to generate H2.This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.

ZnxCd1–xS quantum dot with enhanced photocatalytic H2-production performance

H2 is an important energy carrier for replacing fossil fuel in the future due to its high energy density and environmental friendliness.As a sustainable H2-generation method,photocatalytic H2 production by water splitting has attracted much interest.Here,oil-soluble ZnxCd1-xS quantum dot(ZCS QD)with a uniform particle size distribution were prepared by a hot-injection method.However,no photocatalytic H2-production activity was observed for the oil-soluble ZCS QD due to its hydrophobicity.Thus,the oil-soluble ZCS QD was converted into a water-soluble ZCS QD by a ligand-exchange method.The water-soluble ZCS QD exhibited excellent photocatalytic H2-production performance in the presence of glycerin and Ni^2+,with an apparent quantum efficiency of 15.9%under irradiation of 420 nm light.Further,the photocatalytic H2-generation activity of the ZCS QD was~10.7 times higher than that of the ZnxCd1-xS relative samples prepared by the conventional co-precipitation method.This work will inspire the design and fabrication of other semiconductor QD photocatalysts because QD exhibits excellent separation efficiency for photogenerated electron-hole pairs due to its small crystallite size.

Comparison of deep desulfurization methods in alumina production process

Several methods of deep desulfurization in alumina production process were studied, and the costs of these methods were compared. It is found that most of the S2- in sodium aluminate solution can be removed by adding sodium nitrate or hydrogen peroxide in digestion process, and in this way the effect of S2- on alumina product quality is eliminated. However, the removal efficiency of 2?32OS in sodium aluminate solution is very low by this method. Both S2- and 2?32OS in sodium aluminate solution can be removed completely by wet oxidation method in digestion process. The cost of desulfurization by wet oxidation is lower than by adding sodium nitrate or hydrogen peroxide. The results of this research reveal that wet oxidation is an economical and feasible method for the removal of sulfur in alumina production process to improve alumina quality, and provide valuable guidelines for alumina production by high-sulfur bauxite.

A procedure for design of hydrogen networks with multiple contaminants

It is necessary to reduce hydrogen consumption to meet increasingly strict environmental and product-quality regulations for refinery plants. In this paper, the concentration potential concepts proposed for design of water-using networks are extended to synthesis of hydrogen networks with multiple contaminants. In the design procedure, the precedence of processes is determined by the values of concentration potential of demands.The usage of complementary source pair(s) to reduce utility consumption is investigated. Three case studies are presented to illustrate the effectiveness of the method. It is shown that the design procedure has clear engineering meaning.

Product Vibrational State Distributions of F+CH_(3)OH Reaction on Full-Dimensional Accurate Potential Energy Surface

The hydrogen abstraction reaction of methanol with fluorine atoms can produce HF and CH_(3)O or CH_(2)OH radicals,which are important in the environment,combustion,radiation,and interstellar chemistry.In this work,the dynamics of this typical reaction is investigated by the quasi-classical trajectory method based on a recently developed globally accurate full-dimensional potential energy surface.Particularly,the vibrational state distributions of the polyatomic products CH_(3)O and CH_(2)OH are determined by using the normal mode analysis method.It is found that CH_(3)O and CH_(2)OH are dominantly populated in the ground state when the reactants are at the ground ro-vibrational state.The OH stretching mode,torsional mode,H_(2)CO out-of-plane bending mode and their combination bands in the CH_(2)OH product can be effectively excited once the OH stretching mode of the reactant CH_(3)OH is excited to the first vibrationally excited state.Most of the available energy flows into the HF vibrational energy and the translational energy in both channels,while the radical products,CH_(3)O or CH_(2)OH,receive a small amount of energy,consistent with experiment,which is an indication of its spectator nature.

Successful Application of Hydrocracking Technology Aimed at Prodigiously Boosting Jet Fuel Yield

Recently ＂the hydrocarcking technology aimed at prodigiously boosting jet fuel yield along with improvement of tail-oil quality＂developed by the SINOPEC Research Institute of Petroleum Processing（RIPP） has been successfully applied in commercial scale on the 2.0 Mt/a hydrocracking unit at the SINOPEC Yanshan Branch Company, resulting in implementation of triple functions, viz.： boosting the jet fuel yield, reducing the diesel fuel output and improving the tail-oil quality. This technique has brought about obvious economic and environmental benefts, which can provide a mate-rial basis to bridge the demand gap in jet fuel supply at the new Beijing Airport and will serve as a good ex-ample of SINOPEC’s efforts in the area of transforma-tion of production mode, structure adjustment, product quality upgrading and enhancement of economic ben-efts at the refning enterprise.

Pyrolysis Mechanisms of Quinoline and Isoquinoline with Density Functional Theory

The pyrolysis mechanisms of quinoline and isoquinoline were investigated using the density functional theory of quantum chemistry,including eight reaction paths and a common tautomeric intermediate 1-indene imine.It is concluded that the conformational tautomerism of the intermediate decides the pyrolysis products(C6H6,HC≡C—C≡N,C6H5C≡N and HC≡CH)to be the same,and also decides the total disappearance rates of the reactants to be the same,for both original reactants quinoline and isoquinoline during the pyrolysis reaction.The results indicate that the intramolecular hydrogen migration is an important reaction step,which often appears in the paths of the pyrolysis mechanism.The activation energies of the rate determining steps are obtained.The calculated results are in good agreement with the experimental results.

深红红螺菌吸氢酶缺失突变株在管式光合反应器中的产氢

本研究设计了一种2L分体式管式光合反应器,并研究了深红红螺菌(Rhodospirillum rubrum)吸氢酶缺失突变株在该反应器中分别利用人工光源(持续光照与光暗交替)和自然光的产氢规律。结果表明在人工光照条件下R.rubrum的产氢可维持5d,持续光照和光暗交替条件下(12h:12h)的氢产量可分别达到5752mL/PBR±158mL/PBR和5012mL/PBR±202mL/PBR;自然光条件下,最适产氢光照强度为30000Lux^40000Lux;在此光照条件下,R.rubrum产氢可维持6d^10d,最高氢产量可达到2800mL/PBR。尽管利用自然光的氢产量比利用人工光源氢产量低,但是利用自然光的产氢比较经济,并且该光合产氢系统操作简单,该工艺有望开发为低成本的光合细菌产氢技术。

一种光合细菌产氢反应器的建立

氢能具有燃烧热值高、利用形式多样和产物无污染等优点，被认为是最具有开发潜力的新型能源之一。制取氢气的方式较多，而光合生物制氢因能在常温下进行、对环境无污染而成为清洁能源氢气制取的新方法。光合细菌是理想的产氢微生物之一，光合细菌产氢的发展趋势是利用廉价的自然光作能量来源并使之实用化。

Engineering oxygen vacancy on rutile TiO_2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

Oxygen vacancy（VO） plays a vital role in semiconductor photocatalysis. Rutile TiO2 nanomaterials with controllable contents of VO（0–2.18%） are fabricated via an insitu solid-state chemical reduction strategy, with color from white to black. The bandgap of the resultant rutile TiO2 is reduced from 3.0 to 2.56 e V, indicating the enhanced visible light absorption. The resultant rutile TiO2 with optimal contents of VO（2.07%） exhibits a high solar-driven photocatalytic hydrogen production rate of 734 μmol h-1, which is about four times as high as that of the pristine one（185 μmol h-1）. The presence of VOelevates the apparent Fermi level of rutile TiO2 and promotes the efficient electronhole separation obviously, which favor the escape of photogenerated electrons and prolong the life-time（7.6×103 ns） of photogenerated charge carriers, confirmed by scanning Kelvin probe microscopy, surface photovoltage spectroscopy and transient-state fluorescence. VO-mediated efficient photogenerated electron-hole separation strategy may provide new insight for fabricating other high-performance semiconductor oxide photocatalysts.

A simple green approach to synthesis of sub-100 nm carbon spheres as template for TiO_2 hollow nanospheres with enhanced photocatalytic activities

Carbon spheres（CSs） have attracted great attention given their wide applications in bio-diagnostics, photonic band-gap crystals and drug delivery, etc. The morphology and size of CSs greatly affect their performances and applications. Herein, we report a green and catalyst-free hydrothermal carbonization（HTC） method to synthesize CSs with glucose as carbon precursor. The diameter of CSs can be tuned within a wide range from 450 to 40 nm by controlling the glucose concentration, reaction time and temperature.Using the obtained CSs as template, hollow TiO2 nanospheres（HTNSs） with controllable diameters are prepared via a sol-gel method. As photocatalysts for hydrogen generation, the photoactivity of the HTNSs shows strong dependence upon size,and is much higher than that of solid TiO2. With particle size decreasing, the photoactivity of the obtained HTNSs gradually increases. Without any co-catalyst, the highest photocatalytic hydrogen generation activity is obtained with HTNSs of 40 nm in diameter, which exceeds that of solid TiO2 and commercial P25 by 64 times and 3 times, respectively.